Retractable undercarriage for aircraft



May 18,1943 (5. H. DOWTY RETRACTABLE UNDERCARRIAGE FOR AIRCRAFT FiledMarch 4, 1940 5 Sheets-Sheet l May 18, 1943 s. H. DOWTY 2,319,445

RETRACTABLE UNDERCARRIAGE FOR AIRCRAFT Filed March 4, 1940 3Sheets-Sheet 2.

May 18, 1943 a. H. DOWTY RETRACTABLE UNDERCARRIAGE FOR AIRCRAFT 3Sheets-Sheet 3 Filed March 4, 1940 fire/9 Gears e H Dual :5 g Y theframe being resisted by Patented May 18, 1943 George amen Dowty, ArieCourt, cadmium, England Application March 4, In Great Britain 1940,Serial No.322,182 I March a1, 1939 14 Claims. (Cl. zit-102i Thisinvention relates to, retractable elements of alighting gear foraircraft and is concerned especially with the kind of alighting gear inwhich a leg or equivalent structural element has extending from itsresilient mounting means comprised by a pivoted lever or deformableframe which in turn carries a landing element such as a wheel, swing ofthe lever or deformation of shock-absorber means. Examples of sucharrangements in general are set out in U; S. Patent No. 2,174,315 andthe co-pending applications serial Nos. 273,241 I and 273,624.

An object of this invention is to afford a retraction arrangement inwhich the overall dimensions, especially'in regard tolength of a leg andwheel combination, are decreased during retraction, toreduce stowagespace or avoid awkward structural problems in the aircraft. Anotherobject is to afford some degree of self-locking in the down position ina retractable undercarriage; and a further object is to utilise spacewhich may otherwise be wasted and to preserve externally clean forms.

According to this invention, an element of airerai't alighting gearofthe kindreferred to in which the landing element and its resilientmounting means are movable relative to the leg in a retractionoperation. Preferably, the shockabsorber means alto the resilience ofthe isswungbyaconnectionsuchasarodnvhieh-runsupthroughthelegandispivotally aneccentrlcally ofthelebearinmsothatswin tofthelegaboutits lever.

to transmit a component of the working loads in the shock-absorber, thelink may come ag t a stcpin the leg. preferably over a dead-centre suchthat in no position doesthe shock-absorberapplyanyloadtothelinkexceptsuchasismetq 50 is attached to the channelntting ii. The ref-v erence numeral 26 indicates a movable abutmentwhich cooperates with the channel part I! to by the stop. where thiswhen working loads in the shock-absorber, such ,asthe'load inlandinmmaytendto forcethe mu: into its proper "down" onuon, and u thealighting gear were not ruily extended this force may complete theperation and in,

mung movesthe rod lon imdmally muie le swin the link, thus moves'theshock-absorber. andsointurnshiitsthewheel-earrying In order to avoidtherod or equivalent having.

any case its tendency is to extend rather than to collapse the alightinggear.

In order that it may be clearly understood and more readily carried intoeffect, the invention is.

hereinafter described with reference to the accompanying diagrammaticdrawings, of which:

Figure 1 is a side elevation mainly in section showing in an extendedcondition an undercarriage leg'in accordance with the present in 1vention;

Figure 2 corresponds to Figure 1 and again shows a side elevation of theleg illustrating the parts in a relationship which they assume in afully retracted condition;

Figure 3 is a fragmentary sectional elevation looking in the directionof the arrow of Figure 1, showing the anchorage of the means by whichthe lever arrangement, landing element and as-' sociated shock-absorberare moved bodily in retraction, the parts being indicated in full linesin a fully-extended condition and in chain lines respectively in apartly-retracted condition, and finally in a fully-retracted conditioFigure 4 corresponds to Figure 1 and shows a modified arrangement;whereas Figure 5 corresponds to Figure 3 but deals with the arrangementshown in Figure 4.

Dealing first with Figures 1 to s, the reference numeral I indicates atubular leg which for retraction swings up about the retraction pivot I.Slidable axially of the tubular leg 8 is a rod 8 borneinblocksaandllrThereisanopening I i in the wall of the leg 8 through which'projects therod l2 one end of which is connected to the pivot 12 of the block 8,whereas the other end swings about the iixed pivot ll, which is spacedfrom the retraction pivot 'l but is parallelthereto.. At the lower endthe leg t has a channelsection fitting ll supporting on a pivot II atrailin: lever II, which in turn carries the wheel axle ll, mounting thewheel is. To a lug 20 at the trailing end of the lever i1 is pivoted thecylinder 2| of a telescopic shock-absorber which extends substantiallyparallel with the lever i1 forwardly towards the leg fitting Ii. To thepivot 22 on the plunger 22 of the shock-absorber ,is pivoted a shortlink 24 which extends again forwardly (normally approximately inalignment with the plunger 22) to the pivot 25 by which-it limit upwardswingin of the-link 24. Likewise,

defines the extreme condition.

tion in turn forces the that the lever ii is swung upwards about its,the leg but also in fords a shortening of -38 is attached bothto therod 39, which is virtually sion and extension.

When the aircraft is air-borne the lever ii is right down in theposition determined by the cooperating abutments 21 and 2t.

As stated, the pivot is is fixed and 'consequently as the leg swings inretraction phout the pivot l the distance between the pivots i8 pivotsid and 3) than it is in the fully-extended The result of that difierenceis to force the rod t together with its bearing blocks s and it and theconnecting link it outwards in relation to the retraction pivot i, whichacpivot 22 downwardly so pivot 96. It will be appreciated that as thepivot 22 moves downwardly the lever it has swung up about its pivot itenough to enable the pivot and associated adjacent parts to clear theupper part of the lever ii, which may if necessary be flattened, asindicated at 238.

The nature of the movement which the lever ill makes in relation thestructure in retraction has the chest of at least partly nesting thelever together with the shock-absorber in the not only in the consequentreduction the distance between the extreme rear point oi the wheel andthe lower end or the leg struct It will be observed that in the positionshown the axis of the shock absorber 23. the pivot 22 and the pivot 25are in line. Such an arrangement is particularly desirable in anism oithe leg.

The arrangement illustrated quite easily ofoverall length for retractionequal to the stroke of the wheel, shortening may be Referring now andeven greater degree of achieved.

same object. It will be seen that the tubular leg has an onset fitting32 which may be of channel iorm equivalent of the fitting shown inFigures land 2. Likewise, the fitting 32 carries the pivot is aboutwhich the trailing lever ll swings. The trailing lever I I is providedat a point near the pivot is with the lug 33 incorporating the pinplunger 35 of the shock- 6 and is slidably received by the cylinder 38.the plunger 35 and the cyiinder 33 cooperating to comprise a telescopicshock-absorber. The end of the mote from the plunger incorporates agudgeon pin assembly 3? by means o t-which the cylinder sleeve es and tothe to the leg 6 and the rest oi maximum shock-absorber but in any eventis the cylinder as reis extended the land- 7 employ for retraction theequivalent oi the 75 red I: m the arrangement shown with referenceFigure 5, that the operation of the present arrangement is here exactlythe opposite of that previously described. for whereas in the saidprevious arrangement the internal m housed within the tubular leg 6moves radially away from the retraction pivot I during retraction, themechanism in the pres- 'ent arrangement is caused to approach theretraction pivot i as the leg 6 swings up. It will be observed that thedistance between the endseon pin bly ill and the retraction pivot i isgreatest with the leg in the fully-extended condition owing to the factthat in that condition the pivot point 69 for the connecting rod lee scan be duplicated in a lateral sense and appropriately braced laterallyif required.

It will be apparent from the drawings and description that by reason ofthe fact that the connection of the internal mechanism of the leg withthe lever is disposed quite close to the pivot about which the leverswings, a relatively small movement at the said point of connectionaffords a very much larger movement for the wheel of movement which issmall relative to a corresponding displacement of the associated landingelement. g

It may he mentioned that; it is convenient to and/or for locking theundercarriage in an extended and/or retracted condition. a breakableradius rod operable by jack or equivalent means for retraction and/orextension and for locking in known manner.

l. A retractable element of aircraft alighting gear including a rigidretractabie leg. non-deformable during retraction or extension therwf, aresilient deformable frame extending therefrom for movement up and downunder merely aircraft, a landing gear including a rigid retractable legnon-deformable during retraction or extension thereof, pivotally mountedlever means from said leg for swinging up and down with respect to saidleg during landing and taxiiing of the aircraft, a landing means on saidleg for same upon an aircraft, adjacent said mounting pivot, shockabsorber means affording resilience to said lever. and means includingsaid shockabsorber for interconnecting said lever and said link forswinging said lever with respect to said leg when said leg isrotatedabout said mounting pivot for extension movement. 3. Aretractable element of aircraft aiighting gear including a rigidretractable leg non-deformable during retraction or extension thereof,pivotally mounted lever means extending from said leg for swinging upand down with respect to said leg during landing and taxiing of theelement carried. by said lever, means on said leg for pivotally mountinthe same upon an aircraft, a link pivotally mounted adjacent saidmoimting pivot, shock absorber means affording resilience to said lever,and link means including said shock absorber for interconnecting saidlever andv said link for swinging said lever with respect to said legwhen said leg is rotated about said mcuntin! pivot or extensionmovement, said shock absorber being p tioned in substantial axialalignment with one of said link means extended postion to absorb shockforces. .4.- An element of aircraft alightihg gear including aretractable leg having a connection providing a retraction pivot. forthe same when pivotally mounting the a link pivotally mounted elementcarried by-said lever,

sorber means extending between said lever and sleeve means slidable insaid leg, a connecting rod extending between the assembly comprised a bysaidsleeve means and the interconnected end first mentionedwhen said legis in the gear is mounted, resilient mountingmeans extending from saidleg, alan'ding element carried by'said resilient mounting means,.a linkpivoted to said leg,- telescopic shock-absorber means for affordingresilience to said mounting means substantially in alignment with saidlink in an extended condition of the gear, means for se-i curelydefining the position of said link in the extended condition andconnecting means, housed at least partly in said leg, extending betweensaid link and a pivot spaced from said. retraction pivot to swing.relatively said link and said shock absorber means whereby'to movementof said resilient mounting means in a retraction operation.

5. A'retractable element gear including a retractable leg, 9. linkpivoted to said leg, resilient mounting meansextending fromsaid legcomprised by a lever pivoted to the leg and telescopic shock-absorbermeans extending between a lug on said lever and said link, said shockabsorber means thereby being spaced in relation to said lever andconstitutin therewith a deformable frame, a landing element marriedby'said deformable frame, stop means substantially axially aligning saidlink with said telescopic shock absorber means in an extended conditionof the gear and means connected through said link to swing relativelysaid link and shock absorber means whereby. to effect movement of thesaid resilient mounting means in a retraction operations.

.6. A retractable element of aircraft alightingeffect leg, a landingelement-carried of aircraft alighting said lever, telescopic of saidshock absorber means, and a'pivot spaced from said retraction pivot tomove said sleeve means and associated shock absorber means relatively tosaid leg, whereby to eflect movement of said lever andlanding operation.

8. A-retractable element of aircraft alighting gear including. a legnon-distortable during its retraction and extension movement, a landingelement, an articulated frame connecting said shock absorber relativelyto said element in a retraction landing element to said leg, shockabsorber means in said frame ance to deformation under landing andtaxiing moving said articulated frame leg in a retraction operation.

9. A retractable gear includins a leg non-distortable during itsretraction and extension movement, lever means pivotally connected tosaid leg. a landing element carried by said lever means, a link pivotedto said leg, shock-absorber means connected to said lever and said linkfrom a strut to resiliently resist swinging of said lever under landingand taxiing loads thereby, and means connected to said link for swingingsaid lever relative to said leg in a retraction operation. 10. Aretractable element of aircraft alighting gear including a legnon-distortable'during its retraction and means on said leg, lever meanscarried by said pivot means for movement up and down during landing or.taxiing, a landing element carried by said lever means, a link pivotedto said leg above to afford resilient resistloads, and means forrelative to the otally connected to said link and said lever means andaxially aligned with said link when said leg is in extended by add linkfor securely defining the position of said link in the extendedcondition of the leg, and means connected to and acting through saidlink to swing said link and shock absorber means whereby to effectmovement on said lever relative to said leg during retraction thereof.

11. An element of aircraft ailghtin; gear including a legnon-distortable in retraction and extension movement having a connectionafiording a retractionpivot when the gear is mounted, lever meanspivotally connected to said leg, a lending element carried by saidlevermeans, a

element of aircraft alighting extension movement, pivot.

of said articulated frame shock absorber means pivcondition, meanscarried link pivoted 'to said leg, telescopic shockabsorber' in anextended condisaid leg, extending between said link and a pivot spacedfrom said retraction pivot to swing" relatively said link and said shockabsorber means of said lever with respect to said leg and means wherebyto effect movement of said lever relative to the leg means in aretraction operation.

12. A retractable element of aircraft alighting gear including atraction and extension movement, a link pivoted to said leg, resilientmounting means extending from said leg comprised by lever means pivotedto the leg and having a lug on one end and telescopic shock absorbermeans extending between said lug on said lever means and said link, saidshock absorber, means thereby being spaced in relation to a deformableframe, a landing element carried by said deformable frame, stop meanssubstantially aligning said link with said telescopic shock absorbermeans in an extended condition 01' the leg, and means connected to andacting through said link to swing said link and shock absorber meanswherebyto efl'ect movement of the said resilient mounting means relativeto said leg in a retraction operation. I

13. A retractable element of aircraft alighting gear including a tubularleg non-distortable during its retraction and extension movement andhaving .a, connection afiording a retraction pivot when the gear is mouna pivot spaced from said retraction pivot, lever means pivotailyextending from said leg for swinging relative thereto when said leg isin extended position, a landing element carried by said lever means,

leg non-distortable in resaid lever and constituting therewith shockabsorber means housed in saidleg to afiord resilient resistance toswinging of said lever means with respect to said leg, and meansinterconnecting said shock absorber means and said last mentioned pivotfor sliding said shockabsorber relative to said tubular leg whereby toeflfect movement of said lever means relative to said leg in aretraction operation.

14. An element of aircraft alighting gear in cluding a tubular legnon-distortable in retraction and extension movement and having aconnection affording a retraction pivot when the gear is mountedglevermeans extending from said leg, a landing element carried by said levermeans, sleeve means slidable in said leg, resilient shock absorber meansconnected to said lever and said sleeve means, a pivot spaced from saidretraction pivot, a connecting rod extending between the shock absorberand sleeve assembly and said pivot spaced from said retraction pivotwhereby said sleeve means and a'ssoelated shock absorber means are movedrelatively to said leg, during a retraction operation to eflect movementof said lever means and landing element relative to said leg during theretraction operation.

GEORGE mmam'r DOW'I'Y;

